1. Field of the Invention
The present invention relates to an electron-emitting device, an electron source formed of the electron-emitting device and an image-forming apparatus such as a display device to which the electron source is applied, and more particularly to a surface conduction electron-emitting device with a novel structure, an electron source formed of the surface conduction electron-emitting device, and an image-forming apparatus such as a display device to which the electron source is applied.
2. Related Background Art
The surface conduction electron-emitting device utilizes a phenomenon in which a current is made to flow in an electroconductive film formed on a substrate to emit electrons.
As examples of the surface conduction electron-emitting device, there have been reported a surface conduction electron-emitting device using an SnO2 film (M. I. Elinson Radio Eng. Electron Phys., 10, 1290, (1965)), a surface conduction electron-emitting device using an Au thin film (G. Ditmmer, Thin Solid Films, 9,317 (1972)), a surface conduction electron-emitting device using an In2O3/SnO2 thin film (M. Hartwell and C. G. Fonsted, IEEE Trans. ED Conf., 519 (1975)), a surface conduction electron-emitting device using a carbon thin film (Hisashi Araki, et al: Vacuum, Vol. 26, No. 1, P. 22 (1983)), and so on.
In those surface conduction electron-emitting devices, generally an energization operation called xe2x80x9cformingxe2x80x9d is conducted on the electroconductive film before electron emission to come to a state in which electrons are emitted.
In the specification, the term xe2x80x9cformingxe2x80x9d means that a constant voltage, or a voltage that slowly rises at a rate of, for example, about 1 V/min, is applied to both ends of the electroconductive film so that a current flows in the electroconductive film with the result that the electroconductive film is locally destroyed, deformed or affected into an electrically high resistant state by which electron emission occurs.
It is presumed that the above operation permits the electroconductive film to be partially fissured, and a phenomenon of the electron emission is caused by the existence of the fissure. Where the electron emission actually occurs is not completely elucidated, but the fissure portion and a region surrounding the fissure portion may be called xe2x80x9celectron-emitting portionxe2x80x9d for convenience.
The applicant of the present invention has already proposed many types of surface conduction electron-emitting devices. For example, that the above xe2x80x9cformingxe2x80x9d operation is preferably conducted by applying a pulse voltage to the electroconductive film has been disclosed in Japanese Patent No. 2854385, U.S. Pat. Nos. 5,470,265, 5,578,897, and so on.
In this example, the waveforms of the pulse voltage may be produced by a method in which peak values are held constant as shown in FIG. 5A, or a method in which the peak values are gradually increased. Thus, the waveforms can be appropriately selected taking the configuration and the material of the device, the forming conditions and so on into consideration.
Also, there has been proved that the pulse voltage is repeatedly applied to the electron-emitting device in an atmosphere containing an organic material therein subsequently to the above forming operation, as a result of which a current that flows in the device (device current If) and a current produced with electron emission (emission current Ie) are increased. This operation is called xe2x80x9cactivationxe2x80x9d.
The above operation is that a deposit mainly containing carbon therein is formed in a region including the fissure formed in the electroconductive film through the forming operation, which is disclosed in detail in Japanese Patent Application Laid-Open No. 7-235255, etc.
In the case where the above-described surface conduction electron-emitting device is applied to an image-forming apparatus or the like, a lower power consumption and a higher luminance are further demanded.
Accordingly, as the performance of the electron-emitting device, a demand has been made to heighten the ratio of the emission current Ie to the device current If, that is, the electron emission efficiency as compared with that in the conventional device.
Also, it is needless to say that in improving the above performance, a change of the performance with a time which results from continuing the electron emission must be prevented from increasing more than that in the conventional device.
An object of the present invention is to provide an electron-emitting device excellent in the electron emission characteristic, an electron source using the electron-emitting device, and an image-forming apparatus using the electron source.
In order to achieve the above object, according to the present invention, there is provided an electron-emitting device comprising: a substrate; a pair of electroconductors disposed on a substrate so as to face each other; and a pair of deposit films connected to the pair of electroconductors, respectively, disposed with a gap therebetween and mainly containing carbon, wherein lead is contained in the deposit films in a rate of from 1 mol % to 5 mol % with respect to carbon.
Also, according to the present invention, there is provided an electron-emitting device comprising: a pair of device electrodes disposed on a substrate so as to face each other; electroconductive films connected to the pair of device electrodes and having a fissure between the pair of device electrodes; and a deposit film formed in the fissure and on a region including the fissure, having a gap narrower in width than that of the fissure within the fissure and mainly containing carbon, wherein lead is contained in the deposit film in a rate of from 1 mol % to 5 mol % with respect to carbon.